Mathematical Model for Predicting the Dissolution Behaviors of Hemicelluloses During Cold Caustic Extraction Process

Abstract

SignificanceCold caustic extraction (i.e., CCE) is widely used in mill practice for hemicelluloses removal, and the parameters of which can significantly affect the hemicelluloses dissolution. Therefore, the dissolution behaviors of hemicelluloses under different CCE process parameters have been investigated. The results showed that with the temperature increases, the dissolution of hemicelluloses also increases. However, the effect of alkali content showed complicated, since lower content (<9.0 wt %) was good for the swelling of fibers (i.e., good for hemicelluloses dissolution), but higher content (>9.0 wt %) would accelerate the competing hydration of sodium ions with water and thus limited the dissolution of hemicelluloses. Besides, a mathematical model has been also developed for predicting the hemicelluloses dissolution during CCE process, which can provide a good guidance for enhancing the purification efficiency in the CCE process operation.

Deep Insights into the Atmospheric Sodium Hydroxide–Hydrogen Peroxide Extraction Process of Hemicellulose in Bagasse Pith: Technical Uncertainty, Dissolution Kinetics Behavior, and Mechanism

“…Unlike our previous studies, hydrogen peroxide (H 2 O 2 ) has been also used in this work. According to the literatures, for the three major components in plant cell walls, the links between hemicellulose and cellulose are mainly in the forms of hydrogen bond, van der Waals force, and other weak interactions.…”

“…However, they also artificially distinguished the reaction into two stages without any theoretical basis. In 2019, based on classical chemical reaction kinetic theory, a mathematical model has been first reported for description of the hemicellulose dissolution from fully-bleached bamboo Kraft pulp . However, as no attention was paid to the risk of the activity of the highly-concentrated lye, the reaction overall order was higher than three in the developed model and did not seem to fit the classical collision theory very well.…”

Detailed modeling of the kraft pulping chemistry: carbohydrate reactions

“…When producing dissolving pulp, the hemicelluloses should be removed almost completely (in addition to removing lignin). 51 However, when producing paper grade pulp, it is beneficial to have a relatively high hemicellulose content, because that improves the binding of the cellulosic fibers with each other in the paper. 1 During pulping (also in the case of paper grade pulp) limited removal of hemicelluloses is beneficial for better mass transfer: for example, the lignin molecules can leach out more easily from the cell wall structure, when it becomes more porous, that is, some hemicelluloses are degraded and dissolved.…”